Kayakers and tinfoil hats.

Small boats are always at danger of getting run over by larger vessels. Kayaks, being very small and quite low to the water, are particularly vulnerable and difficult to see.

In the summer of 2003 and 2004 a group set about trying to figure out what was the best way of making their small craft show up on radar.

Of the devices tested the winner was ... wait for it ... a tinfoil hat.

The paper is a good read even for people who don't go kayaking in the open ocean. It pretty well outlines the survival basics of how radar works, how radar reflectors work, or fail to work, and what can be done to make any reflector work better. The same basic dynamics are true if your riding a kayak, a 30' sailboat, or have been set adrift in a life raft.

And yes, it also points out that tinfoil hats have more uses that just keeping the NSA satellites from reading your thoughts.

Read all about it at:
http://www.seagrant.umaine.edu/files/pdf-global/05raref.pdf

There is also a more comprehensive study, but far less fun study because they left out the tinfoil hat, of commercial radar reflectors at: (Looks like I blew the address the first time. The correct address is):
http://www.maib.gov.uk/cms_resources.cfm?file=/Radar%20reflectors%20report.pdf

Brought to my attention at:
http://www.cruisersforum.com/forums/f122/radar-reflectors-35612.html

Edited to correct address of second pdf.

Hmm, seems like some people are going to be mad for making the NSA's job of tracking them a hole lot easier On the other hand it might be a good business opportunity selling "stealth" foil hats.

This is interesting. During the early years of radar, fishermen lashed metal barrels to their masts as radar reflectors.

I wonder if a space blanket would work?

Maybe an aluminized propeller beanie, for that pulsed return signal...

Reminds me of the RAF Vulcan Bomber story practicing precision bombing on a featureless desert in the US using airborne RADAR during the early sixties. The USAF were amazed that they hit their impossible RADAR target they were given, thinking that the RAF had a secret technology way ahead of the USA at the time.

Apparently the RAF aircrew wifes had gone for a picnic out in the desert at a predetermined location, then at a specific time they all opened and closed their car boot doors which gave a blinking RADAR return to the Vulcan bombers enough to pinpoint their ground target using with the car boot RADAR location as a offset geographical reference.

A purpose-built radar reflector is a good idea. Occasionally known as the "Mongolian Ghost Trap" (can't recall where I read that) the idea is to hoist something that purposefully retro-reflects radar.
Radar won't see the target if the incoming beam isn't directed back where it came from (basic stealth concept). There are devices that look like a bunch of corners made of metal to hoist on your masthead.

THese things are important because there are a lot of merchant vessels out there being steered by "otto"
Otto-pilot. Everyone else is asleep.

Another threat to one's nautical well-being can be mentioned. Submarines.
Submarines can't hear sailboats. (or kayaks) A submarine coming to periscope depth could collide with your silent boat and sink you. Might not even hear you go crunch either.

(I came very, very close to hitting a sailboat one night.)

Now if only jet boats on rivers used radar!

Kayaking is similar to motorcycling - you may legally have right of way, but in the real world, you're the one who's dead. So high-visibility colors (a big part of why so many kayaks are yellow) and use your eyes and especially your ears to avoid conflicts in the first place. Since I don't create any engine noise, I can hear a motorized boat coming long before they see me.

I'm fortunate that on a river, there is only a narrow channel that a motorized boat can take. I just head closer to shore when I hear one coming and then only need to worry about their wake (bonus rapid!).

Note I posted the wrong address for the second paper. The correct address is:
http://www.maib.gov.uk/cms_resources.cfm?file=/Radar%20reflectors%20report.pdf

More suitable for a person selecting a radar reflector for a boat it goes into some depth reviewing quite a few different commercially available models.

"Radar won't see the target if the incoming beam isn't directed back where it came from (basic stealth concept)."

A guy in Oregon once told me that he had some friends who constantly exceeded the speed limit on the local roads, and they told him that they avoided radar traps by loosely crinkling HD aluminum foil and covering their hubcaps with it.

Would this really have the desired effect?

Sue

So if I read the foil hat report right they performed well but a kayak is still too small of a target to get noticed easily and its signal is usually lost in the clutter filter of the radar unit.

So besides staying out of the shipping lanes what else can you do?
Is there any way to make a small powered radar beacon that would give a radar signal, hopefully warning ships that you are there?
Maybe it could pulse the signal in such a way that they know you are a small craft instead of another drifting oil drum.

You are looking for a RACON, they are used by the USCG on entrance buoys.

They transmit a signal (usually a morse code letter such as "A" .-) everytime it receives a RADAR signal.

This morse code letter will appear on the vessel's RADAR directly opposite of where the contact (kayak) is.

Unfortunately, RACON's are expensive, or were. That may have changed. Contact ACR and see if they carry them and for how much.

On the Western Rivers and canals, we report all small boats that we see, via VHF-FM radio, in general broadcasts to other boats in the area. These small boats scare the hell out of us!!!!

Thanks Wildman, but wouldn't transmitting a buoy ID be confusing?

Still If they are cheap and small enough the RACON beacon might be good to have especially if visibility gets poor.

Certainly something I will look into a bit more. Thanks again.

The other idea in the article that wasn't really tested was an enhanced life vest/jacket that would have radar reflective material built into it. That way there is less of a need for a awkward mast on the kayak. A mast changes the dynamics and balance of a very small craft. But combine the enhanced life jacket with a radar reflective hat my be commercially viable.
Still, the best alternative is to stay out of shipping lanes (not always possible), hug the shorelines, paddle in tight groups and be visible to the naked eye with bright reflective colours.

As far as submarines colliding with kayaks -- thanks for the laugh, because even small littoral subs (of which the US doesn't have anymore) don't come that close into shore to worry kayaker's who rarely venture more than a mile from shore.

ACR, or other electronic companies MAY have RACON's specifically made for small boats.

I've also seen these on offshore platforms. It really great to see one on an offshore platform that has had navigation light failure. Besides helping you notice the unlighted platform, the code allows you to better know your position since that platform will stand out positively identified in a sea of platforms surrounding you.

You could fit an AIS, or radar repeater, system to a boat but kayaks don't usually have power system that could handle such loads. I'm thinking on of the 6" radar reflector balls held 4 or 5' high with a flexible fiberglass pole set up behind the paddled would work.

I ran into this while searching the internets.
http://www.prlog.org/10227763-altus-vrb-...ted-states.html


It looks like somebody else has been working on the idea already.
It still seems a bit short range to me.

That's a good workable range for a m/v to get your signal and avoid you. Most operators run their RADARs between .25 - 1.5 mile ranges depending on where they are.

I don't know. It's not reflecting the radar away from the car because the crinkles have lots of folds in them to act as a retro-reflector.
On the other hand, from head-on the crinkles on the top of the hubcap are "coming" while the ones on the bottom are "going" which has the potential to confuse things. Still, there are lots of other radar-reflectors on the car that would reflect strongly.

I think they were pulling your leg.

Other- subs don't come close in-shore when the water is shallow ("shallow" would be a Classified term if specifics were given). Lookout though if it's deep. I think the boomers submerge in Hood's Canal which might be a recreational area.
But I agree, it's not a *big* threat. Especially if you make regular thumping noises that sound man-made.

The crinkled foil bit,is a farce as, Radar guns have Range-finders,&Chronographs built in,Distance x seconds = MPH,or a cop could just use his wristwatch & a fixed position,either way,If they even think you are speeding,You are speeding,until you can prove otherwise!Sorry for the hijack,of the thread!

Submerged subs surfacing inshore are not a viable concern based on my knowledge and experience. Subs running on the surface are a threat as is any other M/V, for the same reasons.

Subs usually transit with escorts, who clear the inshore channels of all other traffic. The ports that subs normally transit into and out of are generally known and are allowed for by the locals. Subs do occasionally make Ports of Calls in unusual places such as New Orleans during the Mardi Gras, but these are again, to be expected. There are other non-sub based ports that see regular transits of subs, such as Groton, Cn and Cape Canaveral, Fl.

Boomers have air, sea, and subsurface escorts out from their portrs to the Continental shelf. Even someone who has no familiarization with submarine operations will take notice of that amount of activity. Someone will be along shortly if you're in a place that they don't want you in.

(Sorry to do this) Chief maybe your experience wasn't the complete picture or represents only certain areas?

I drove subs for awhile (OOD Submerged). That's why I'm saying what I'm saying. Made many unescorted surface transits. Surfaced from deep water close enough inshore to read the signs sometimes. Almost sank a sailboat one night in the Bahamas and nearly a torpedo retriever in the VaCapes.

We're invisible most of the time. That's why it's so hard to know what we're up to :-)

I roger your last but the actual thread was in regards to kayaks and there are not many kayaks far enough out to accommodate a sub's draft. I'm not saying that it's impossible to occur but it would definitely be rare.

That's what diesel-electrics and sailboats have in common, they operate extremely quietly.

Did you ever do boomers? I have several experiences with both Attack boats and Boomers as OOD on Patrol Boats and as Nav LPO on Corvettes in the Bahamas areas and southward. You gotta love a Port of Call in Port Canaveral, Fl.

Wasn't that a candy bar commercial in the 1980s? Little girl and grandpa in a rowboat, a big Russian boomer (Typhoon?) comes up with them on the missle deck, Capt comes out and gets offered some candy?

Good thought, esp if you're near a sub base. Man, I'd be pissed if I got hit by one of them though. We'd have some words. (probably "Blub blub, gurgle gurgle")

I was Fast Attack.

Port Canaveral - yep. The small craft were annoying until the young ladies started removing their clothing and smiling for the few sailors above decks. The periscope camera stopped moving in search when that happened.


In general, kayakers don't have to worry about submarines but.... you can never be completely sure until you're holding your kayak over your head on dry land :-)

Sue, the hubcaps really have little to do with the return signature. The headlights give the best return, with the reflectors at the back of the bulb. You can tell the hubcap guys that, if they chew the tinfoil, the radio waves created from the contact with the fillings in their teeth, will jam police radios...